battle of the mocking frameworks
DESCRIPTION
From Sela Developer Practice 2013 In the real world, applications are so complex, that in order to test a component in isolation, you need a new set of tools. Without using a mocking framework it is impossible to write easy to read and maintain unit tests. The problem is that there are a lot of different frameworks to choose from – each has its merits and shortcomings. How can you choose the correct framework? What is the difference between the free alternatives to the costly commercial options and why should you care about error message… By the end of this talk you'll understand why you need a mocking framework and which framework is the best for your project.TRANSCRIPT
SELA DEVELOPER PRACTICEMay 5-9, 2013
Dror Helper
Battle of the mocking frameworks
About.Me
• Developing software (professionally) since 2002
• Disclaimer: I used to work at Typemock
• Blogger: http://blog.drorhelper.com
This is a unit test
[Test]
public void AddTest()
{
var cut = new Calculator();
var result = cut.Add(2, 3);
Assert.AreEqual(5, result);
}
This is not a real unit test
The problem - dependencies
Unit test
Code under test
Dependency Dependency
The solution – Mocking!
Unit test
Code under test
DependencyFake object(s)
What is a “Mock object”?
“mock objects are simulated objects that mimic the behavior of real objects in controlled ways”[From Wikipedia]
I prefer to call them “Fakes”
What does a mocking framework do?
1.Create fake objects
2.Set behavior on fake objects
3.Verify method was called (Mock)
4.Much more
.NET Mocking frameworks
Isolation Frameworks
Open Source
Commercial
Isolator
JustMock
RhinoMocks
Moq
nSubtitute
FakeItEasy
NMock3
Free
MS Fakes
Usage statistics
Moq45%
Rhino Mocks23%
None9%
FakeItEasy6%
Nsubstitute6%
Isolator4%
Moles2%
MS Fakes2%
JustMocks2%
Other 1%
:// . / /2012/5/4/ - - - - - -http osherove com blog annual poll which isolation framework do you- - - .use if any html
Choosing the right framework is important
1.Married into your code
2.Saves/waste time
3.Affects design
Round 1 - API
• Readable
• Discoverable
• Simple
• Extensive
• Error messages
API summery
Error msg Parameters Mock<T> SPE Readability
+ Explicit Yes No + Moq
- Explicit No No + Rhino-Mocks
+ Explicit No Yes + FakeItEasy
+ Explicit No No + nSubtitute
? Explicit Yes No - NMock3
+ Implicit No Yes + Isolator
- Explicit No Yes + JustMock
N/A Explicit Yes No - MS Fakes
Round 2 - Robustness
• What happens when:• Code under test API changed• Code under test internal change
Future proof
Round 3
Constrained
Unconstrained
Unconstraint vs. Constraint
Isolation Frameworks
Constraint
Unconstraint
Isolator
JustMock
RhinoMocks
Moq
nSubtitute
FakeItEasy
NMock3
MS Fakes
Constrained
• Fake by inheritance• Force architecture
• Dependency injection (DI)• Code by interfaces (LSP)
• Boxing of the unfakeable
Real object
Fake object
Unconstrained
• Profiler API based• Can fake almost anything
• 3rd party systems• Legacy code
• Design your code not for testability
• Can be used as if they are constrained
Real Object
Dependency Fake
Nickels and dimes
Constraint frameworks are free – can you afford them?
How much does it cost if every task takes 1 hour more?
How much does it cost not to use unit tests?
Round 4 - deployment
Constraint
Deployment – the bottom line
MS Fakes JustMock Isolator Unconstraint
Only on VS11 Install on each machine.
Install on each machine.Auto-run correct version
Nothing (NuGet)
Dev machine
Only on TFS2012 Install on each machine.
Install or use AutoDeploy
Nothing Build Machine
Only TFS2012 Environment varsJustMockRunnerBuild Tasks
Environment varsTMockRunnerBuild Tasks
Just run it CI
Only VS11 profilers
Limited linker (nCover, dotTrace)
Use LinkerVS11 profilers
Works! Profilers Support
Summery – what to choose?
Thank You